A. Field of the Invention
The present invention relates to face gears, in particular to face gears provided on the handle shaft of spinning reels.
B. Description of Related Art
Generally spinning reels have a reel main body, a rotor supported for free rotation on the main body, and a spool that peripherally winds on fish line, provided toward the front of the rotor. The rotor rotates unitarily with a pinion gear provided peripherally on the spool axle. The spool shuttles back and forth by means of a level-wind mechanism that is driven by an intermediate gear that meshes with the pinion gear. The pinion gear meshes with a face gear (master gear) provided on a handle rotation axle (handle shaft) that is orthogonal to the pinion gear, and is rotated by rotation of the handle. The face gear is usually formed incorporated with the handle shaft. Conventionally zinc alloys have been comparatively widely used as a material for cheaply manufacturing the face gear which includes the handle shaft, and for maintaining its strength.
Generally with spinning reels, designing to make them lightweight to elevate casting performance is important. Further, it is also important to improve corrosion resistance in order to prolong their life-span. With the above-noted conventional face gear, however, since zinc alloys of high relative density that are inferior in corrosion resistance are utilized, their heavy weight makes lightweight design difficult, and moreover improving corrosion resistance is problematic.
Therein, consideration has been given to using aluminum alloys as a face gear material for designing the face gear to be lightweight, and further to using stainless steel alloys as a face gear material in order to improve the corrosion resistance. Due to the inferior strength of aluminum alloys compared to zinc alloys, along with inferior manufacturing precision wherein die-casting or the like is to be carried out, however, when utilizing aluminum alloys as a face gear material, the strength and precision of the teeth of the face gears deteriorates. Furthermore, while stainless steel alloys are of better strength compared to zinc alloys, owing to poor workability along with problems generally in injection molding, it is difficult to improve precision; when employing stainless steel alloys the precision of the face gear teeth is liable to deteriorate.
It is an object of the present invention to provide for a lightened-weight face gear while maintaining its strength and precision.
Another object of the present invention is to provide for improvement of corrosion resistance of a face gear while maintaining its strength and precision.